Hydrogen Abstraction from the C15 Position of the Cholesterol Skeleton

Fabrizio Palumbo, Inmaculada Andreu*, Maria Brunetti, Max Schmallegger, Georg Gescheidt, Dmytro Neshchadin, Miguel A. Miranda

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Cholesterol (Ch) is an integral part of cell membrane, where it is prone to oxidation. In humans, oxidation of Ch is commonly linked to various pathologies like Alzheimer's disease, atherosclerosis, and even cancer, which proceed via mechanisms involving enzymatic and free radical pathways. The latter begin with hydrogen abstraction (HA) from Ch by a reactive free radical. It has been established that the most efficient HA from Ch occurs at C7, although HA from C4 by peroxyl radicals has recently been observed. Conversely, HA from Ch positions other than the thermodynamically preferred C7 or C4 has never been reported. We have designed a Ch derivative where a benzophenone moiety is linked to C7 by a covalent bond. This mirrors a specific orientation of Ch within a confined environment. Product analysis and time-resolved spectroscopic studies reveal an unprecedented HA from C15, which is a thermodynamically unfavorable position. This indicates that a specific topology of reactants is crucial for the reactivity of Ch. The relative orientation of the reactants can also be relevant in biological membranes, where Ch, polyunsaturated fatty acids, and numerous oxidizing species are confined in highly restricted and anisotropic environments.

Original languageEnglish
Pages (from-to)15184-15191
Number of pages8
JournalJournal of Organic Chemistry
Volume84
Issue number23
DOIs
Publication statusPublished - 6 Dec 2019

ASJC Scopus subject areas

  • Organic Chemistry

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